btrfs: abtract out range locking in clone ioctl()

The range locking in btrfs_ioctl_clone is trivially broken out into it's own
function. This reduces the complexity of btrfs_ioctl_clone() by a small bit
and makes that locking code available to future functions in
fs/btrfs/ioctl.c

Signed-off-by: Mark Fasheh <mfasheh@suse.de>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>

fs/btrfs/ioctl.c

@@ -2470,6 +2470,26 @@ out:
 	return ret;
 }
 
+static inline void lock_extent_range(struct inode *inode, u64 off, u64 len)
+{
+	/* do any pending delalloc/csum calc on src, one way or
+	   another, and lock file content */
+	while (1) {
+		struct btrfs_ordered_extent *ordered;
+		lock_extent(&BTRFS_I(inode)->io_tree, off, off + len - 1);
+		ordered = btrfs_lookup_first_ordered_extent(inode,
+							    off + len - 1);
+		if (!ordered &&
+		    !test_range_bit(&BTRFS_I(inode)->io_tree, off,
+				    off + len - 1, EXTENT_DELALLOC, 0, NULL))
+			break;
+		unlock_extent(&BTRFS_I(inode)->io_tree, off, off + len - 1);
+		if (ordered)
+			btrfs_put_ordered_extent(ordered);
+		btrfs_wait_ordered_range(inode, off, len);
+	}
+}
+
 static noinline long btrfs_ioctl_clone(struct file *file, unsigned long srcfd,
 				       u64 off, u64 olen, u64 destoff)
 {
@@ -2598,21 +2618,7 @@ static noinline long btrfs_ioctl_clone(struct file *file, unsigned long srcfd,
 	truncate_inode_pages_range(&inode->i_data, destoff,
 				   PAGE_CACHE_ALIGN(destoff + len) - 1);
 
-	/* do any pending delalloc/csum calc on src, one way or
-	   another, and lock file content */
-	while (1) {
-		struct btrfs_ordered_extent *ordered;
-		lock_extent(&BTRFS_I(src)->io_tree, off, off + len - 1);
-		ordered = btrfs_lookup_first_ordered_extent(src, off + len - 1);
-		if (!ordered &&
-		    !test_range_bit(&BTRFS_I(src)->io_tree, off, off + len - 1,
-				    EXTENT_DELALLOC, 0, NULL))
-			break;
-		unlock_extent(&BTRFS_I(src)->io_tree, off, off + len - 1);
-		if (ordered)
-			btrfs_put_ordered_extent(ordered);
-		btrfs_wait_ordered_range(src, off, len);
-	}
+	lock_extent_range(src, off, len);
 
 	/* clone data */
 	key.objectid = btrfs_ino(src);